The purpose of the cruise control system is to automatically maintain a vehicle speed set by the driver. When the cruise control is activated, speed is maintained or increased by means of an electronically controlled cable attached to the accelerator assembly. If the vehicle must be slowed to maintain the speed that was set by the driver, the cruise control system allows the throttle return spring to close the throttle.
If driving conditions require sudden acceleration after the cruise control has been set, speed can be increased in the normal manner by manually pressing the accelerator. The cruise control is disengaged if the brakes (or clutch, with manual transaxle) are applied.
The minimum speed for setting the cruise control is 38.6 km/h (24 mph). When cruise control is operating, the CRUISE indicator lamp is on in the instrument cluster.
The cruise control system is capable of monitoring internal software and hardware faults as well as external faults in the connectors and wire harness. If a fault is detected, cruise control is stopped immediately, and the program logic and hardware logic independently prevent the cruise control from opening the throttle.
The cruise control will function in temperatures ranging from -40°C to 85°C (-40°F to 185°F). Maximum temperature could cause the regulation properties to be out of tolerance, but the safety shutdown will still be operational under maximum temperature conditions. If high temperature interferes with cruise control operation, the actuator electromagnetic clutch will open, and the throttle return spring will close the throttle, unless the accelerator pedal is pressed.
Cruise Control Actuator
The cruise control actuator is a single component system. The electronic controls are combined in one housing with the mechanical components. The actuator is mounted in the passenger compartment.
The mechanical components of the cruise control actuator are listed below:
| • | Permanent field DC motor |
| • | Single stage belt transfer gearing |
| • | Spindle drive |
| • | Electromagnetic clutch |
| • | Clutch plate with cable attachment |
| • | End switches |
| • | Plastic housing with noise reduction cover |
| • | Damping unit for clutch plate slap |
The mechanical parts are not serviceable. The entire actuator must be replaced if it is mechanically defective.
The electronics of the cruise control system include the following items:
| • | A microprocessor which controls speed regulation and monitors input signals |
| • | A clutch activation circuit which energizes the clutch magnet to couple the DC motor to the control cable |
| • | A driver circuit which activates the DC motor in a clockwise or counterclockwise direction |
| • | A control unit for lamp activation |
The electronic parts are not serviceable. The entire actuator must be replaced if there is an electronic defect in one of the systems.
Cruise Control Switch
After the main switch is turned on and the neutral position of the lever switch is detected by the cruise control actuator, the following operations can be performed by using the cruise control lever switch:
Set
If the cruise control is ON and the minimum speed is 38.6 km/h (24 mph), but not more than 155 km/h (96 mph), the target speed can be set by selecting the SET button for 10-300 milliseconds. If SET is selected for more than 300 milliseconds, the cruise control will be activated in the COAST function. If the accelerator is pressed by the driver after the cruise control has been set, the previous target speed will be maintained when the accelerator is released. If the accelerator is pressed by the driver until the actual speed is more than 35 km/h (22 mph) over the target speed, or until the vehicle exceeds 160 km/h (99 mph), the cruise control will disengage.
Coast
If a target speed has been set and COAST is selected for at least 300 milliseconds, the throttle will return to idle, and the vehicle will coast. When the COAST switch is released, the current speed will be maintained as the new target speed. If the vehicle speed drops below 32.2 km/h (20 mph) while coasting, the cruise control will be disengaged. If the switch is released between 32.2 km/h (20 mph) and 38.6 km/h (24 mph), the minimum target speed of 38.6 km/h (24 mph) will be used.
Resume
If the cruise control is ON, and the system was disengaged by using the brake or clutch, exceeding the maximum speed, failing to maintain the minimum speed, or exceeding the target by more than 35 km/h (22 mph), the last memorized speed can be reset by selecting RESUME if the time since disengagement is not greater than 5 seconds. The RESUME function is selected by switching to RESUME for 10-300 milliseconds. If the actual speed is below the target speed when RESUME is selected, the vehicle will accelerate at 3.4 km/h per second (2.1 mph/second) until the vehicle is within 10 km/h (6 mph) of the target speed, and then acceleration will be reduced to achieve a smooth transition from acceleration to cruising. If the actual speed is above the target speed when RESUME is selected, the throttle will be allowed to return to idle until the target speed is achieved. RESUME can be canceled by selecting SET, and then the current speed will be maintained as the new target speed.
Accelerate
If the cruise control is ON, and the ACCEL switch is selected for more than 300 milliseconds, the vehicle will accelerate. The acceleration is maintained at the rate of 3.4 km/h per second (2.1 mph/second) as long as vehicle performance is sufficient; otherwise, full throttle is applied. When the switch is released, the current speed will be stored and used as the new target speed. The ACCEL switch cannot be used for acceleration above 155 km/h (96 mph). If 155 km/h (96 mph) is attained, acceleration will stop and 155 km/h (96 mph) will be set as the new target speed.
Tap-Up
If the cruise control has been set, and RESUME is selected again for more than 10 milliseconds, but less than 300 milliseconds, the target speed will increase by 2 km/h (1.2 mph) for each time that the RESUME button was selected, or tapped. If the driver has used the accelerator to increase speed over 8 km/h (5 mph) over the current target speed, a tap-up signal will be interpreted as a normal SET signal. The cruise control will not accept a tap-up target speed above 155 km/h (96 mph). If the actual speed has fallen 16.1 km/h (10 mph) below the target speed, tap-up signals are not accepted.
Tap-Down
If the cruise control is already set and SET is selected for 10-300 milliseconds, the target speed will decrease by 2 km/h (1.2 mph) for each time that SET was selected, or tapped. Tap-down signals will not be accepted for a target speed below 38.6 km/h (24 mph). If the vehicle speed has increased to 8 km/h (5 mph) over the target speed, the cruise control system will interpret a tap-down signal as a SET.
If the cruise control is turned OFF with the main switch, all cruise control functions are stopped, the actuator cable is driven toward idle, and the electromagnetic clutch for the cable actuator is opened. The cable actuator clutch is not opened immediately to accomplish a smooth transition in vehicle speed. If the cruise control is OFF for more than 5 seconds, the memorized target speed is erased.
